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  #1  
Old 01-19-2020, 12:06 AM
lndwarrior lndwarrior is offline
 
Join Date: Mar 2015
Location: Cloverdale CA
Posts: 243
Default Earthx Etx680 and semi-cold weather

3 year old battery. Have had hard starting issues after the plane sits for a few weeks.

Today i went to fly after 18 days in between flights. Nightime temps have been in the mid-thirties. Up to the 50s during the day.

On startup the battery was clearly straining. After about a 30 minutes of flying the battery was back up to full charge.

Im wondering if this is others experience? From what I've read this doesnt seem to be normal.
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  #2  
Old 01-19-2020, 06:40 AM
sailvi767 sailvi767 is offline
 
Join Date: Sep 2010
Location: Charlotte NC
Posts: 1,019
Default

Did you put a load on the battery for a minute or so prior to cranking to warm it up? Keep in mind that regardless of the battery a cold engine is harder to turn over.
G
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  #3  
Old 01-19-2020, 07:33 AM
vic syracuse vic syracuse is offline
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Location: Locust Grove, GA
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Do make sure you don't have a parasitic leak from the battery. I've seen a number of batteries replaced wrongly due to this.

Take off either lead on the battery and place a ammeter in between the battery and the lead. Use the mili-amp setting on the meter. You should have zero amps.

The biggest mistake I have seen causing this comes from the installation of the newer 406 MHZ ELT's. They require a connection to aircraft power, and since they are usually installed in the rear of the aircraft a conection is made directly to the battery due to it's proximity, such as in RV-8's and 10's.

The other cause is from internal cabin lighting that is wired directly to the battery. Those lights can get left ON and may not be bright enough to see that they are on. If left on, it can take several weeks to a month to completely discharge the battery, and if you are regularly flying, you won't notice it.

Vic
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  #4  
Old 01-19-2020, 07:59 AM
Northernliving Northernliving is offline
 
Join Date: May 2005
Location: Boston, MA
Posts: 301
Default Self Discharge?

Quote:
Originally Posted by lndwarrior View Post
3 year old battery. Have had hard starting issues after the plane sits for a few weeks.

Today i went to fly after 18 days in between flights. Nightime temps have been in the mid-thirties. Up to the 50s during the day.

On startup the battery was clearly straining. After about a 30 minutes of flying the battery was back up to full charge.

Im wondering if this is others experience? From what I've read this doesnt seem to be normal.
This may have something to do with it.
https://batteryuniversity.com/learn/...self_discharge

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  #5  
Old 01-19-2020, 08:22 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 4,566
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Quote:
Originally Posted by Northernliving View Post
This may have something to do with it.
https://batteryuniversity.com/learn/...self_discharge

That discharge rate is for flooded lead acid. Sealed Lead acid, like the Odyssey is much lower. Forget the exact number, but I thought it was in the range of 2% per month.

Larry
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  #6  
Old 01-19-2020, 09:15 AM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 1,975
Default odyssey

According to their website, the odyssey can be stored for about 24 months at 25C/77F, losing about 65% of its charge. Works out to about 2.7% per month...
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  #7  
Old 01-19-2020, 09:18 AM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 168
Default Random thoughts...

The OP didn't mention if he was using a battery maintainer or not -- I suspect not...

Typically, the usage model for aircraft systems, (engines, batteries, etc.) is not the same as an Automobile, but we seem to expect the exact same behavior of these disparate systems.

If you had a car that just sat in the garage, our outside for weeks at a time you might expect it to start with a little sluggishness.

As for me, I've always used a battery maintainer/charger appropriate to the battery installed, because I know I'm not going to fly every day (I wish the opposite were true ) and I've never had an issue with a dead battery, sluggish start, etc.

YMMV

Cheers!
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Retired Firmware Guy and Airplane Builder

2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231

Aided and abetted building a number of other RV's.
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  #8  
Old 01-19-2020, 09:33 AM
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bkervaski bkervaski is offline
 
Join Date: Mar 2017
Location: Birmingham, Alabama
Posts: 1,391
Default

Just as a data point, EarthX is a LifePO4 (not on that chart).

LiFePO4 is also very resistant to self-discharge. Remember the old days when your NiCad batteries would go dead in a month or so just sitting on the shelf? That’s because they self discharge at rate of about 1% per day. LiFePO4 has a typical self discharge rate of 5% per month. In other words, it takes six months for a LiFePO4 battery to self discharge to the same level a conventional battery reaches in just thirty days.

Important! If you're going to use a battery maintainer be sure to take electronic ignition manufacturer guidelines into consideration.
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Last edited by bkervaski : 01-19-2020 at 09:38 AM.
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  #9  
Old 01-19-2020, 09:51 AM
lndwarrior lndwarrior is offline
 
Join Date: Mar 2015
Location: Cloverdale CA
Posts: 243
Default thx

Quote:
Originally Posted by vic syracuse View Post
Do make sure you don't have a parasitic leak from the battery. I've seen a number of batteries replaced wrongly due to this.

Take off either lead on the battery and place a ammeter in between the battery and the lead. Use the mili-amp setting on the meter. You should have zero amps.

The biggest mistake I have seen causing this comes from the installation of the newer 406 MHZ ELT's. They require a connection to aircraft power, and since they are usually installed in the rear of the aircraft a conection is made directly to the battery due to it's proximity, such as in RV-8's and 10's.

The other cause is from internal cabin lighting that is wired directly to the battery. Those lights can get left ON and may not be bright enough to see that they are on. If left on, it can take several weeks to a month to completely discharge the battery, and if you are regularly flying, you won't notice it.

Vic
Great suggestions Vic. I will check these out. I appreciate you taking the time to respond.

My led panel lights are LED and on a rheostat, so this could be the problem. I know you can't see them during the day on anything but the highest setting.
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  #10  
Old 01-19-2020, 09:57 AM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 168
Default

Quote:
Originally Posted by bkervaski View Post
Just as a data point, EarthX is a LifePO4 (not on that chart).

LiFePO4 is also very resistant to self-discharge. Remember the old days when your NiCad batteries would go dead in a month or so just sitting on the shelf? Thatís because they self discharge at rate of about 1% per day. LiFePO4 has a typical self discharge rate of 5% per month. In other words, it takes six months for a LiFePO4 battery to self discharge to the same level a conventional battery reaches in just thirty days.

Important! If you're going to use a battery maintainer be sure to take electronic ignition manufacturer guidelines into consideration.
I assume you're referring to this note for P-Mag?


"OPERATING NOTES: Battery Chargers: Some styles of ground (110 volt) chargers will hammer the battery with charge pulses as part of their normal cycle. Such hammering is not a typical buss state and can cause problems for the ignition if it is powered ON during such a charge. So as a normal guideline, KEEP IGNITIONS POWERED OFF WHILE (GROUND) CHARGING."
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Brian Decker
Retired Firmware Guy and Airplane Builder

2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231

Aided and abetted building a number of other RV's.
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